FIG. 13 is a circuit diagram of a display device using conventional coil components. In FIG. 13, inverter circuit 100 is formed of coil components 101, 102, and stabilizer circuit 103. Coil component 101 includes primary coil 101A and secondary coil 101B, and one end of secondary coil 101B is connected to one end of lamp 300. The other end of coil component 101 and one end of coil component 2 are connected to stabilizer circuit 103. The other end of coil component 102 is connected to the other end of lamp 300. Also, driving coil 200 is connected to the primary coil side of coil component 101, 102.
As preceding technical document information about this application, for example, Japanese Laid-open Patent 2002-231034 is commonly known.
In a display device using such a conventional coil component, there arises a problem of flicker on the display screen.
That is, in the conventional configuration described above, one end of lamp 300 as shown in FIG. 14 and the other end of lamp 300 are separately connected to coil components 101, 102. Consequently, the phase of current flowing to one end of lamp 300 as shown in FIG. 14 s deflected from the phase of current flowing to the other end as shown by current waveform (a) and current waveform (b). That is, current waveform (b) includes T2−T1 (sec.) time lag (phase lag) as against current waveform (a).
As an ideal configuration, current waveform (a) and current waveform (b) are desirable to be even in phase of the current as shown in FIG. 16. In this case, light emission of the lamp can be obtained as shown in FIG. 17A to FIG. 17G. In FIG. 17A to FIG. 17G, blank portion 301 is a light emitting portion, and shaded portion 302 is a light non-emitting portion. Even in case such emission of light is repeated, the light emitting portion and the light non-emitting portion are constant, and if the frequency is high enough, the person will not feel the flicker because human eyes are unable to follow it.
However, in a display device using a conventional coil component, because of the above-mentioned reason, since the phases are deflected from each other as shown by current waveform (a) and current waveform (b) in FIG. 14, the states of light emission become as shown in FIG. 15A to FIG. 15G in which the non-emitting portion (shaded portion 302) shifts with the lapse of time. As a result, flicker is generated on the display screen of the display device.
Also, in place of lamp 300, even when bar-like lamp 400, 500 is connected as shown in FIG. 18, the output currents of coil component 101 and coil component 102 respectively flow into one end and the other end of lamp 400 and lamp 500, causing similar phase deflection to take place, and flicker is generated on the display screen of the display device.